Communication device, communication method thereof, information processing device, control method thereof, and computer-readable storage medium

ABSTRACT

A communication device communicates a radio frame including a preamble and a data field of a physical layer (PHY). The preamble includes an L-STF (Legacy Short Training Field), an L-LTF (Legacy Long Training Field), an L-SIG (Legacy Signal Field), an EHT-SIG-A (Extremely High Throughput Signal A Field), an EHT-STF, and an EHT-LTF, and the EHT-SIG-A includes a field indicating a standard that the radio frame complies with.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.17/412,660, filed on Aug. 26, 2021, which is a Continuation ofInternational Patent Application No. PCT/JP2020/004216, filed Feb. 5,2020, which claims the benefit of Japanese Patent Application No.2019-036405 filed Feb. 28, 2019, both of which are hereby incorporatedby reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a communication device, a communicationmethod thereof, an information processing device, a control methodthereof, and a program and, more particularly, to a communicationcontrol technique in a wireless LAN.

Background Art

As a communication standard concerning a wireless LAN (Wireless LocalArea Network), the IEEE (Institute of Electrical and ElectronicsEngineers) 802.11 standard is known. In the IEEE802.11ax standard thatis the latest standard of the IEEE802.11 standard series, not only ahigh peak throughput but also improvement of a communication speed undera congestion situation is implemented using OFDMA (OrthogonalFrequency-Division Multiple Access) (see PTL 1).

Currently, in order to further improve throughput, a study group calledIEEE802.11EHT (Extremely High Throughput) has been formed as a successorstandard of IEEE802.11ax.

CITATION LIST Patent Literature

-   PTL 1: Japanese Patent Laid-Open No. 2018-050133

As many standards have been formulated so far, it is expected that newstandards will appear in the future. On the other hand, concerning aradio frame complying with a new standard, a communication devicecomplying with only an old-generation standard needs to continuouslyread the frame until it becomes clear that the radio frame complies withthe standard to which the self-device is not adaptable, and this leadsto an increase in power consumption.

SUMMARY OF THE INVENTION

The present invention provides a technique of preventing a communicationdevice from unnecessarily continuing to read a radio frame uponreceiving a radio frame complying with a standard to which the device isnot adaptable.

According to one aspect of the present invention, there is provided acommunication device that transmits or receives a radio frame includinga preamble and a data field of a physical layer (PHY), wherein thepreamble includes an L-STF (Legacy Short Training Field), an L-LTF(Legacy Long Training Field), an L-SIG (Legacy Signal Field), anEHT-SIG-A (Extremely High Throughput Signal A Field), an EHT-STF (EHTShort Training Field), and an EHT-LTF (EHT Long Training Field), and theEHT-SIG-A includes a field indicating a standard that the radio framecomplies with.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing an example of the configuration of a network;

FIG. 2 is a block diagram showing an example of the functionalconfiguration of a communication device;

FIG. 3 is a block diagram showing an example of the hardwareconfiguration of the communication device;

FIG. 4 is a flowchart showing an example of the procedure of processingto be executed in the communication device;

FIG. 5 is a view showing an example of the PHY frame structure of an EHTSU PPDU;

FIG. 6 is a view showing an example of the PHY frame structure of an EHTER PPDU;

FIG. 7 is a view showing an example of the PHY frame structure of an EHTMU PPDU; and

FIG. 8 is a view showing an example of the PHY frame structure of an EHTTB PPDU.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, embodiments will be described in detail with reference tothe attached drawings. Note, the following embodiments are not intendedto limit the scope of the claimed invention. Multiple features aredescribed in the embodiments, but limitation is not made to an inventionthat requires all such features, and multiple such features may becombined as appropriate. Furthermore, in the attached drawings, the samereference numerals are given to the same or similar configurations, andredundant description thereof is omitted.

(Network Configuration)

FIG. 1 shows an example of the configuration of a wireless communicationnetwork according to this embodiment. This wireless communicationnetwork includes one access point (AP) and three stations (STAs). Notethat each of an AP 102 and an STA 103 complies with IEEE802.11EHT(Extremely High Throughput), and is configured to be capable ofperforming wireless communication complying with standards definedbefore the IEEE802.11EHT standard. An STA 104 is an STA that isadaptable to the IEEE802.11ax standard but not to IEEE802.11EHT. Also,an STA 105 is an STA that is adaptable to communication standards afterthe IEEE802.11EHT. Note that the name “IEEE802.11EHT” is provided forconvenience, and can be another name when the standard was established,but this specification and the appended claims are to cover all thestandards that can support the processing to be described later. In thefollowing description, in a case in which a specific device is notreferred to or the like, the access point may be referred to as “AP” andthe station (terminal) may be referred to as “STA” without referencenumerals. Note that in FIG. 1, the wireless communication networkincluding one AP and three STAs is shown as an example, but the numbersof these communication devices may be more or less than shown. In anexample, no AP may exist when the STAs communicate with each other. InFIG. 1, the communicable area of the network formed by the AP 102 isindicated by a circle 101. Note that this communicable area may cover alarger area, or may cover only a smaller area. Note that it may beunderstood that EHT is an acronym of Extreme High Throughput.

(Device Configuration)

FIG. 3 shows an example of the hardware configuration of each of thecommunication devices (the AP and the STAs). The communication deviceincludes, as an example of its hardware configuration, a storage unit301, a control unit 302, a function unit 303, an input unit 304, anoutput unit 305, a communication unit 306, and an antenna 307.

The storage unit 301 is formed by both of a ROM and a RAM or one ofthem, and stores programs for performing various kinds of operations tobe described later and various kinds of information such ascommunication parameters for wireless communication. Note that otherthan the memories such as a ROM and a RAM, a storage medium such as aflexible disk, a hard disk, an optical disk, a magnetooptical disk, aCD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, or a DVD maybe used as the storage unit 301.

The control unit 302 is formed by, for example, one or more processorssuch as a CPU and an MPU, an ASIC (Application Specific IntegratedCircuit), a DSP (Digital Signal Processor), an FPGA (Field ProgrammableGate Array), or the like. Here, CPU is an acronym of Central ProcessingUnit, and MPU is an acronym of Micro Processing Unit. The control unit302 executes the programs stored in the storage unit 301, therebycontrolling the entire device. Note that the control unit 302 maycontrol the entire device by cooperation of the programs stored in thestorage unit 301 and an OS (Operating System).

In addition, the control unit 302 controls the function unit 303 toexecute predetermined processing such as image capturing, printing, orprojection. The function unit 303 is hardware used by the device toexecute predetermined processing. For example, if the device is acamera, the function unit 303 is an image capturing unit and performsimage capturing processing. For example, if the device is a printer, thefunction unit 303 is a printing unit and performs print processing. Forexample, if the device is a projector, the function unit 303 is aprojection unit and performs projection processing. Data to be processedby the function unit 303 may be data stored in the storage unit 301, ormay be data communicated with another AP or STA via the communicationunit 306 to be described later.

The input unit 304 accepts various kinds of operations from a user. Theoutput unit 305 performs various kinds of outputs for the user. Here,the output by the output unit 305 includes, for example, at least one ofdisplay on a screen, audio output by a loudspeaker, vibration output,and the like. Note that both the input unit 304 and the output unit 305may be implemented by one module, like a touch panel.

The communication unit 306 controls wireless communication complyingwith the IEEE802.11 standard series, or controls IP communication. Thecommunication unit 306 is a so-called radio chip, and may itself includeone or more processors and memories. In this embodiment, thecommunication unit 306 can execute processing complying with at leastthe IEEE802.11ax standard. In addition, the communication unit 306controls the antenna 307 to transmit and receive radio signals forwireless communication. The device communicates contents such as imagedata, document data, or video data with another communication device viathe communication unit 306. The antenna 307 is an antenna that cantransmit and receive signals in at least any one of, for example, asub-GHz band, 2.4 GHz band, 5 GHz band, and 6 GHz band. Note that thefrequency band (and a combination of frequency bands) to which theantenna 307 is adaptable is not particularly limited. The antenna 307may be one antenna, or may be a set of two or more antennas to performMIMO (Multi-Input and Multi-Output) transmission/reception. FIG. 3 showsone antenna 307, but the antenna may include two or more antennas (twoor more sets of antennas) that are adaptable to different frequencybands.

FIG. 2 shows an example of the functional configuration of each of thecommunication devices (the AP and the STAs). As an example, thecommunication device includes a wireless LAN control unit 201, a frameanalysis unit 202, a frame generation unit 203, a UI control unit 204, astorage unit 205, and an antenna 206.

The wireless LAN control unit 201 is configured to include circuits thattransmit/receive radio signals to/from another wireless LAN device (forexample, another AP or STA) using the antenna 206, and programsconfigured to control these. The wireless LAN control unit 201 executescommunication control of wireless LAN such as transmission of a framegenerated by the frame generation unit 203 and reception of a radioframe from another wireless LAN device in accordance with the IEEE802.11standard series. The frame analysis unit 202 analyzes a radio framereceived via the wireless LAN control unit 201. This analysis is done byreading the radio frame from the head. Note that the frame analysis unit202 analyzes the physical layer (PHY) preamble of a radio frame, as willbe described later, thereby operating to discard a radio frame for astandard (version) the communication device does not comply with. Sincethis allows the communication device to early interrupt analysis of aradio frame of a type the self-device does not comply with, the powerconsumption can be reduced. The frame generation unit 203 generates, forexample, a radio frame including data to be transmitted to another AP orSTA. In accordance with a standard the self-device complies with or, insome cases, a standard the partner device of communication complieswith, the frame generation unit 203 generates a radio frame complyingwith a standard that enables communication between the self-device andthe partner device. For example, if the communication device complieswith IEEE802.11EHT, and the partner device complies with IEEE802.11ax, aradio frame complying with the IEEE802.11ax is generated andtransmitted/received. The UI control unit 204 is configured to includehardware concerning user interfaces (UIs) such as a touch panel andbuttons configured to accept an operation on the communication device bythe user (not shown) of the communication device, and programsconfigured to control these. Note that the UI control unit 204 also hasa function of, for example, presenting information to the user, such asdisplay of an image or the like or audio output. The storage unit 205 isconfigured to include a storage device such as a ROM (Read Only Memory)or a RAM (Random Access Memory) configured to store programs to beexecuted by the communication device and various kinds of data.

(Procedure of Processing)

The procedure of processing to be executed by the communication deviceas described above will be described next. FIG. 4 shows an example ofthe procedure of processing to be executed by the communication devices(the AP and the STAs) according to this embodiment, which comply withIEEE802.11EHT. First, the communication device decides an operatingfrequency band (step S401). The decision of the operating frequency bandis performed by the AP. That is, if the communication device is an AP,the operating frequency band is decided by a user operation of thecommunication device, or the like. If the communication device is anSTA, it is decided that the STA operates in the operating frequency banddecided by the AP of the connection destination. Note that the operatingfrequency band can be one of frequency bands of, for example, 2.4 GHz, 5GHz, and 6 GHz. If another usable frequency band exists, the frequencyband may be used. Note that in the following description, a frequencyband of 2.4 GHz or 5 GHz, which is usable by communication devicescomplying with old-generation communication standards, is used.

After that, the communication device decides a standard a radio frameshould comply with when transmitting the radio frame. Note that in thisprocessing example, the communication device determines whether thestandard is IEEE802.11EHT (step S402). The communication device decidesthe communication standard to be used based on, for example, thestandard the self-device complies with and the standard the partnerdevice complies with. For example, if both the communication device andthe partner device comply with IEEE802.11EHT, the communication devicedecides to use the IEEE802.11EHT. If one of the communication device andthe partner device complies with a successor standard of IEEE802.11EHT,and the other complies with IEEE802.11EHT but not with the successorstandard, the communication device decides to use the IEEE802.11EHT. Ifone of the communication device and the partner device complies withIEEE802.11EHT, but the other complies with only an old-generationstandard, the communication device decides to use the old-generationstandard. For example, in communication between the AP 102 and the STA103, since both comply with IEEE802.11EHT, it is decided to use theIEEE802.11EHT. In communication between the AP 102 and the STA 104,since the AP 102 complies with IEEE802.11EHT, but the STA 104 complieswith only IEEE802.11ax, it is decided to use the IEEE802.11ax. Incommunication between the AP 102 and the STA 105, since the STA 105complies with a successor standard of IEEE802.11EHT, but the AP 102 donot comply with the successor standard, it is decided to use theIEEE802.11EHT. Note that the “successor standard” here includes, forexample, Wave2 of IEEE802.11EHT, and the like. That is, in thisembodiment, different versions of IEEE802.11EHT, which are obtained byfurther improving, after formulation, the IEEE802.11EHT standard thatuses radio frames to be discussed below, are also handled as successorstandards.

Upon deciding to use the IEEE802.11EHT (YES in step S402), thecommunication device sets a field (for example, a Version subfield to bedescribed later) indicating the type of the standard in the radio frameand sets a value indicating EHT in the field (step S403). Note that upondeciding to use a standard after the IEEE802.11EHT, the communicationdevice can prepare a field indicating the type of the standard and set avalue indicating the standard to be used in the field. In this case, instep S402, the communication device determines whether to use a standardafter IEEE802.11EHT. If a standard after IEEE802.11EHT is to be used, anappropriate value can be set in the field indicating the type of thestandard. The communication device generates a radio frame (PPDU)including such a field indicating the type of the standard. Note thatPPDU is an acronym of Physical Layer (PHY) Protocol Data Unit. On theother hand, upon deciding to use an old-generation standard (legacystandard) before IEEE802.11EHT (NO in step S402), the communicationdevice generates a radio frame (PPDU) in accordance with theold-generation standard. Then, the communication device transmits thegenerated radio frame (step S404). Note that radio frame transmissionhere also includes transmission of a beacon. That is, if thecommunication device is an AP, the communication device generates andtransmits a beacon in accordance with the communication standard theself-device complies with. Note that if the self-device does nottransmit a radio frame and only receives a radio frame from the partnerdevice, the communication device may omit the processes of steps S402 toS404.

Processing at the time of signal reception will be described next. Thecommunication device receives a radio frame from the partner device(step S405). Note that the partner device here indicates the partnerdevice with which the communication device directly communicateswirelessly. For example, if the communication device is an STA, thepartner device is the connected AP. If the communication device is anAP, the partner device is the STA connected to the self-device. Thecommunication device determines whether the received radio frame is aradio frame of a legacy standard (step S406). Here, the legacy standardindicates the IEEE802.11a/b/g/n/ax standards. Upon determining that aradio frame of a legacy standard is received (YES in step S406), thecommunication device reads the whole radio frame (step S407). On theother hand, upon determining that a radio frame of a standard after theIEEE802.11ax standard, that is, a standard after IEEE802.11EHT isreceived (NO in step S406), the communication device reads the fieldindicating the type of the standard as described above (step S408). Thecommunication device then determines whether the self-device isadaptable to the standard of the type indicated by a value set in theread field (whether an operation complying with the standard ispossible) (step S409). For example, a communication device complyingwith IEEE802.11EHT determines whether the value set in the field is avalue corresponding to IEEE802.11EHT. If the self-device is adaptable tothe type of the standard of the radio frame (YES in step S409), thecommunication device continues the analysis of the radio frame and readsthe whole radio frame (step S410). When the read of the radio frame isended, the communication device continues the analysis while handlingdata stored in the data field as a frame of a MAC (Medium AccessControl) layer. On the other hand, if the self-device is not adaptableto the type of the standard of the radio frame (NO in step S409), thecommunication device does not analyze the radio frame anymore anddiscards the radio frame (step S411). This makes it possible to preventthe communication device from unnecessarily continuing to read the radioframe of the standard to which the device is not adaptable and preventwaste of the power consumption of the communication device. Note thatthe communication device may perform only transmission of a radio frame,and if no radio frame is received, the processing from step S405 may beomitted.

In FIG. 4, as an example, the AP generates a Beacon frame includinginformation indicating the standard the self-device complies with andsends it. The STA transmits a Probe Request frame based on the Beaconframe. The AP determines whether the Probe Request frame is a legacyframe, and if the Probe Request frame is not a legacy frame, determineswhether the Probe Request frame is generated in accordance with thestandard the self-device complies with. If the Probe Request frame is alegacy frame or is generated in accordance with the standard theself-device complies with, the AP performs analysis in the MAC layer.The AP can recognize, by the analysis in the MAC layer, that the frameis a Probe Request frame, and transmit the Probe Response frame. On theother hand, if the Probe Request frame is generated in accordance with astandard the self-device does not comply with, the AP discards theframe. Note that since the frame is discarded without performinganalysis in the MAC layer, the AP does not recognize that the frame is aProbe Request frame. For this reason, the AP does not transmit the ProbeResponse frame. As described above, the communication device may executethe signal transmission processing in steps S402 to S404 and the signalreception processing in steps S405 to S411 in different communicationopportunities, or may execute these processes as a series of processesin one communication opportunity.

Examples of the structures of radio frames complying with IEEE802.11EHTare shown in FIGS. 5 to 8. FIG. 5 shows an example of an EHT SU (SingleUser) PPDU that is a PPDU for single-user communication, and FIG. 6shows an example of an EHT MU (Multi User) PPDU for multi-usercommunication. FIG. 7 shows an example of an EHT ER (Extended Range)PPDU for long distance transmission, and FIG. 8 shows an example of anEHT TB (Trigger based) PPDU that is transmitted from the STA as aresponse to a trigger frame transmitted from the AP. The EHT ER PPDU isused when the communication area should be extended in communicationbetween an AP and a single STA.

The PPDU includes fields including an STF (Short Training Field), an LTF(Long Training Field), and a SIG (Signal Field). As shown in FIG. 5, thehead portion of the PPDU includes an L (Legacy)-STF 501, an L-LTF 502,and an L-SIG 503 for ensuring backward compatibility with theIEEE802.11a/b/g/n/ax standards. Note that each of frame formats shown inFIGS. 6 to 8 includes an L-STF (L-STF 601, 701, or 801), an L-LTF (L-LTF602, 702, or 802), and an L-SIG (L-SIG 603, 703, or 803). Note that theL-LTF is arranged immediately after the L-STF, and the L-SIG is arrangedimmediately after the L-LTF. Note that each of the structures shown inFIGS. 6 to 8 further includes an RL-SIG (Repeated L-SIG, an RL-SIG 504,604, 704, or 804) arranged immediately after the L-SIG. In the RL-SIGfield, the contents of the L-SIG are repeatedly transmitted. The RL-SIGis used to enable a receiver to recognize that this PPDU complies with astandard after the IEEE802.11ax standard, and may be omitted inIEEE802.11EHT in some cases. In addition, a field for enabling thereceiver to recognize that this PPDU complies with the IEEE802.11EHT maybe provided in place of the RL-SIG.

The L-STF is used for detection of a PHY frame signal, AGC (AutomaticGain Control), timing detection, or the like. The L-LTF is used forhighly accurate frequency/time synchronization, obtainment ofpropagation channel information (CSI: Channel State Information), or thelike. The L-SIG is used for transmitting control information includinginformation such as a data transmission rate and a PHY frame length. Alegacy device complying with the IEEE802.11a/b/g/n/ax standards candecode the above-described various kinds of legacy fields.

Each PPDU further includes an EHT-SIG (EHT-SIG-A 505, 605, 705, or 805and EHT-SIG-B 606) arranged immediately after the RL-SIG and used fortransmitting control information for EHT. Each PPDU further includes anSTF for EHT (EHT-STF 506, 607, 706, or 806) and an LTF for EHT (EHT-LTF507, 608, 707, or 807). Each PPDU includes, after these controllingfields, a data field 508, 609, 708, or 808 and a Packet extension field509, 610, 709, or 809. The portion including the fields from the L-STFto the EHT-LTF of each PPDU is referred to as a PHY preamble. Note thatthe respective fields of each PPDU may not necessarily be arranged inthe order shown in each of FIGS. 5 to 8, or may include a new field notshown in each of FIGS. 5 to 8.

Note that each of FIGS. 5 to 8 shows the PPDU that can ensure thebackward compatibility as an example. However, if it is unnecessary toensure the backward compatibility, for example, the legacy fields may beomitted. In this case, for example, the EHT-STF and EHT-LTF are used inplace of the L-STF and the L-LTF to establish synchronization. In thiscase, the EHT-STF and one of the plurality of EHT-LTFs after the EHT-SIGfield can be omitted.

The EHT-SIG-A 505 and 705 included in the EHT SU PPDU and the EHT ERPPDU include an EHT-SIG-A1 and an EHT-SIG-A2 necessary for reception ofthe PPDU, respectively, as shown in Tables 1 and 2 below. In addition,the EHT-SIG-A 605 of the EHT MU PPDU shown in FIG. 6 includes anEHT-SIG-A1 and an EHT-SIG-A2 necessary for reception of the PPDU, asshown in Tables 3 and 4 below. Furthermore, the EHT-SIG-A 805 of the EHTTB PPDU shown in FIG. 8 includes an EHT-SIG-A1 and an EHT-SIG-A2necessary for reception of the PPDU, as shown in Tables 5 and 6 below.In this embodiment, in any frame structure, a “Version” subfieldindicating which standard a radio frame is generated is included in 3bits in the head of the EHT-SIG-A1.

TABLE 1 Bit Bit Position Subfield Count Description EHT- B0-B2 Version 3This subfield indicates a version SIG-A1 of the frame. “0” is set if theframe is a EHT-frame. B3 Format 1 “1” is set for an EHT PPDU and an EHTER PPDU to distinguish them from an EHT TB PPDU. B4 Beam 1 “1” is set ifthe pre-EHT of the Change PPDU is arranged in a space different from thefirst symbol of the EHT-LTF, or “0” is set if the pre-EHT is mappedsimilarly to the first symbol. B5 UL/DL 1 This subfield indicateswhether the PPDU is for UL or DL, and has the same value as TXVECTORUPLINK_FLAG. B6-B9 MCS 4 This subfield indicates the value of theModulation and Coding Scheme. In a case of an EHT SU PPDU, n = 0, 1, 2,. . . , 11 (12 to 15 are reserved). In a case of an EHT ER SU PPDU andBandwidth = 0, n = 0, 1, 2 (3 to 15 are reserved areas). In a case of anEHT ER SU PPDU and Bandwidth = 1, n = 0 for MCS 0 (1 to 15 are reservedareas). B10 DCM 1 This subfield indicates whether Dual CarrierModulation is applied to the data field. If “0” is set in the STBCfield, “1” is set. (If both the DCM and STBC fields are “1”, neither ofthem is applied) If DCM is not applied, “0” is set. B11- BSS 6 6-bitnumber for identifying the B16 Color BSS B17 Reserved 1 Reserved fieldB18- Spatial 4 This subfield indicates whether B21 Reuse Spatial Reuseis allowed during transmission of this PPDU. The value of Spatial Reusefield encoding shown in the separate table is set. B22- Band- 2 In acase of an EHT SU PPDU: B23 width “0” is set for 20 MHz, “1” is set for40 MHz, “2” is set for 80 MHz, or “3” is set for 160 MHz (80 + 80 MHz).In a case of an EHT ER SU PPDU: “0” is set for 242-tone RU, or “1” isset for upper 106-tone RU of 20 MHz. B24- GI + LTF 2 This subfieldindicates B25 Size the Guard Interval period and the EHT- LTF size. “0”is set for 1 × EHT-LTF and 0.8 μs GI, “1” is set for 2 × EHT-LTF and 0.8μs GI, “2” is set for 2 × EHT- LTF and 1.6 μs GI, “3” is set if both theDCM and STBC fields are “1” and for 4 × EHT-LTF and 0.8 μs GI, or “3” isset for 4 × EHT-LTF other than the above case and 3.2 μs GI. B26- NSTS 2This subfield indicates the B28 And number of space-time streams Mid-and the midamble period for amble frame synchronization. Period- If theDoppler field is icity “0”, “(the number of space-time streams) - 1” isset If the Doppler field is “1”, B23 and B24 indicate the number ofspace-time streams. B25 is “0” if the midamble period is 10, or “1” ifthe midamble period is 20.

TABLE 2 Bit Bit Position Subfield Count Description EHT- B0-B6 TXOP 1Transmission Opportunity SIG- If TXOP_DURATION of A2 TXVECTOR isUNSPECIFIED and there is no period information, 127 is set. IfTXOP_DURATION of TXVECTOR is smaller than 512, a value smaller than 127is set to set NAV. At this time, if B0 is “0”, FLOOR of TXOP_DURATION/8(round down) is set in B1 to B6. If B0 is “1”, FLOOR of (TXOP_DURATION -512)/8 is set in B1 to B6. B7 Coding 1 “0” is set for BCC (BinaryConvolutional Code), or “1” is set for LDPC (Low Density Parity Check).B8 LDPC Extra 1 This subfield indicates the Symbol presence/absence ofan extra Segment OFDM symbol segment for LDPC. B9 STBC 1 “1” is set inthis field if STBC (Space-Time Block Coding) is used and the DCMsubfield is “0”, “1” is also set if neither DCM nor STBC is applied, or“0” is set otherwise. B10 Beamformed 1 “1” is set if beamformingsteering is applied to the waveform of SU transmission. B11- Pre-FEC 2“0” is set if the Pre-FEC Padding B12 Padding Factor is 4, “1” is set ifthe Pre- Factor FEC Padding Factor is 1, “2” is set if the Pre-FECPadding Factor is 2, or “3” is set if the Pre-FEC Padding Factor is 3.B13 PE 1 Disambiguity field of Packet Disambiguity Extension B14Reserved 1 Reserved field B15 Doppler 1 “1” is set if either of thefollowing conditions is met: the number of OFDM symbols in the datafield is larger than “the value indicated by the midamble period + 1”,and a midamble exists, and the number of OFDM symbols in the data fieldis equal to or smaller than “the value indicated by the midambleperiod + 1”, no midamble exists, and the channel changes rapidly. B16-CRC 4 The CRC of the EHT-SIG-A (26 B19 bits of A1 and 16 bits up to B15of A2, that is, 42 bits in total) field up to here. B20- Tail 6 An areato set “0” to indicate the B25 end portion to a trellis convolutiondecoder.

TABLE 3 Bit Bit Position Subfield Count Description EHT- B0-B2 Version 3This subfield indicates a SIG-A1 version of the frame. “0” is set if theframe is a EHT-frame. B3 UL/DL 1 This subfield indicates whether thePPDU is for UL or DL, and has the same value as TXVECTOR UPLINK_FLAG.B4-B6 SIGB 3 This subfield indicates the MCS MCS of the EHT-SIG-B field.“0” is set for MCS 0, “1” is set for MCS 1, “2” is set for MCS 2, “3” isset for MCS 3, “4” is set for MCS 4, or “5” is set for MCS 5. “6” and“7” are reserved areas. B7 SIGB 1 “1” is set if the HT-SIG- DCM B fieldis modulated using DCM. B8-B13 BSS 6 6-bit number for identifying Colorthe BSS B14-B17 Spatial 4 This subfield indicates whether Reuse SpatialReuse is allowed during transmission of this PPDU. The value of SpatialReuse field encoding shown in the separate table is set. B18-B20 Band- 3“0” is set for 20 MHz, width “1” is set for 40 MHz, or “3” is set for160 MHz (80 + 80 MHz). When the SIGB Compression field is “0”, “4” isset if only the secondary 20 MHz is puncturing in 80 MHz preamblepuncturing, “5” is set if two 20 MHz of the secondary 40 MHz arepuncturing in 80 MHz preamble puncturing, “6” is set if only thesecondary 20 MHz is puncturing in 160 (or 80 + 80) MHz preamblepuncturing, or “7” is set if only the secondary 40 MHz is puncturing in160 (or 80 + 80) MHz preamble puncturing. If the SIGB field is “1”, thevalue between “4” to “7” means “reserved”. B21-B24 Number 4 When theSIGB Compression of field is “0”, this subfield indicates EHT- thenumber of OFDMA symbols SIG-B in the EHT-SIG-B. Symbols If the number ofOFDM symbols or in the EHT-SIG-B is smaller than MU- 16, the numberobtained by sub- MIMO tracting 1 from the number of Users OFDM symbolsin the EHT-SIG- B is set. If at least one receiving terminal has set thecapability of supporting the number of EHT SIG-B OFDM symbols largerthan 16 to “0”, “15” is set to indicate that the number of OFDM symbolsin the EHT-SIG-B is 16. If all the receiving terminals have set thecapability of supporting the number of EHT SIG-B OFDM symbols largerthan 16 to “0” and the data rate of the EHT-SIG-B is smaller than MCS 4which does not use DCM, “15” is set to indicate that the number of OFDMsymbols in the EHT-SIG-B is equal to or larger than 16. When the SIGBCompression field is “1”, the value set here means the number obtainedby subtracting 1 from the number of MU-MIMO users. B25 SIG 1 “1” is setif a Common Com- field exists in the EHT- pression SIG-B. B26-B27 GI + 2This subfield indicates LTF Size the Guard Interval period and the EHT-LTF size. “0” is set for 4 × EHT-LTF and 0.8 μs GI, “1” is set for 2 ×EHT- LTF and 0.8 μs GI, “2” is set for 2 × EHT-LTF and 1.6 μs GI, or “3”is for 4 × EHT-LTF and 3.2 μs GL B28 Doppler 1 “1” is set if either ofthe following conditions is met: the number of OFDM symbols in the datafield is larger than “the value indicated by the midamble period + 1”,and a midamble exists, and the number of OFDM symbols in the data fieldis equal to or smaller than “the value indicated by the midambleperiod + 1”, no midamble exists, and the channel changes rapidly.

TABLE 4 Bit Bit Position Subfield Count Description EHT- B0-B6 TXOP 1Transmission Opportunity SIG- If TXOP_DURATION of A2 TXVECTOR isUNSPECIFIED and there is no period information, 127 is set. IfTXOP_DURATION of TXVECTOR is smaller than 512, a value smaller than 127is set to set NAV. At this time, if B0 is “0”, FLOOR of TXOP_ DURATION/8(round down) is set in B1 to B6. If B0 is “1”, FLOOR of (TXOP_DURATION -512)/8 is set in B1 to B6. B7 Reserved 0 Reserved field B8-B10 Number of3 This subfield indicates the number EHT-LTF of EHT-LTFs. Symbols And“0” is set for one EHT-LTF, “1” is Midamble set for two EHT-LTFs, “2” isset for Periodicity four EHT-LTFs, “3” is set for six EHT-LTFs, or “4”is set for eight EHT-LTFs. When the Doppler field is “1”, B8 and B9indicate the number of EHT-LTF symbols, and B10 indicates the midambleperiod. B11 LDPC Extra 1 This subfield indicates the Symbolpresence/absence of an extra Segment OFDM symbol segment for LDPC. B12STBC 1 When the number of users of each RU (Resource Unit) is not largerthan 1, “1” is set to indicate that STBC is used for encoding. B13-Pre-FEC 2 “0” is set if the Pre-FEC Padding B14 Padding Factor is 4, “1”is set if the Pre-FEC Factor Padding Factor is 1, “2” is set if thePre-FEC Padding Factor is 2, or “3” is set if the Pre-FEC Padding Factoris 3. B15 PE 1 Disambiguity field of Packet Disambiguity Extension B16-CRC 4 The CRC of the EHT-SIG-A (26 B19 bits of A1 and 16 bits up to B15of A2, that is, 42 bits in total) field up to here. B20- Tail 6 An areato set “0” to indicate the B25 end portion to a trellis convolutiondecoder.

TABLE 5 Bit Position Subfield Bit Count Description EHT- B0-B2 Version 3This subfield indicates a SIG-A1 version of the frame. “0” is set if theframe is an EHT-frame. B3 Format 1 “1” is set for an EHT PPDU and an EHTER PPDU. Otherwise, “0” is set. B4-B9 BSS Color 6 6-bit number foridentifying the BSS. B10-B13 Spatial 4 This subfield indicates whetherReuse 1 Spatial Reuse is permitted. Spatial Reuse is applied to thefirst 20 MHz band when the Bandwidth is 20, 40, or 80 MHz. Spatial Reuseis applied to the first 40 MHz band when the Bandwidth is 160 MHz/80 +80 MHz. The value of SPATIAL_REUSE shown in another table is set.B14-B17 Spatial 4 This subfield indicates whether Reuse 2 Spatial Reuseis permitted. Spatial Reuse is applied to the second 20 MHz band whenthe Bandwidth is 20, 40, or 80 MHz. Spatial Reuse is applied to thesecond 40 MHz band when the Bandwidth is 160 MHz/80 + 80 MHz. The valueof SPATIAL_REUSE shown in another table is set. B18-B21 Spatial 4 Thissubfield indicates whether Reuse 3 Spatial Reuse is permitted. SpatialReuse is applied to the third 20 MHz band when the Bandwidth is 20, 40,or 80 MHz. Spatial Reuse is applied to the third 40 MHz band when theBandwidth is 160 MHz/80 + 80 MHz. SPATIAL_REUSE shown in another tableis set. B22-B25 Spatial 4 This subfield indicates whether Reuse 4Spatial Reuse is permitted. Spatial Reuse is applied to the fourth 20MHz band when the Bandwidth is 20, 40, or 80 MHz. Spatial Reuse isapplied to the fourth 40 MHz band when the Bandwidth is 160 MHz/80 + 80MHz. The value of SPATIAL_REUSE shown in another table is set. B26Reserved 1 Reserved field B27-B28 Bandwidth 2 “0” is set for 20 MHz, “1”is set for 40 MHz, “2” is set for 80 MHz, and “3” is set for 160 (80 +80) MHz.

TABLE 6 Bit Bit Position Subfield Count Description EHT- B0-B6 TXOP 1Transmission Opportunity SIG-A2 If TXOP_DURATION of TXVECTOR isUNSPECIFIED and there is no period information, 127 is set. IfTXOP_DURATION of TXVECTOR is smaller than 512, a value smaller than 127is set to set NAV. At this time, if B0 is “0”, FLOOR of TXOP_DURATION/8(round down) is set in B1 to B6. If B0 is “1”, FLOOR of (TXOP_DURATION -512)/8 is set in B1 to B6. B7-B15 Reserved 9 Reserved field B16-B19 CRC4 The CRC of the EHT-SIG-A (29 bits of A1 and 16 bits up to B15 of A2,that is, 45 bits in total) field up to here. B20-B25 Tail 6 An area toset “0” to indicate the end portion to a trellis convolution decoder.

For example, if a radio frame is generated in accordance with theIEEE802.11EHT standard, 0 is stored in the “Version” subfield. If aradio frame is generated in accordance with a successor standardimmediately after the IEEE802.11EHT standard or a standard of asuccessor version after a change, 1 is stored in the “Version” subfield.Similarly, when the number of types of standards increases, differentvalues of 2, 3, . . . , 7 are defined as the values to be set in the“Version” subfield in correspondence with the standards. As in Tables 1to 6 described above, when a predetermined number of bits in the head ofthe EHT-SIG-A are used as the Version subfield, the communication devicecan early determine whether the self-device complies with the standardthe radio frame complies with. As a result, the communication device canearly end read (decoding processing) of a radio frame generated inaccordance with a standard the self-device does not comply with, andpower consumption associated with the read of the radio frame can besuppressed.

Note that in the examples of Tables 1 to 6, the Version subfield isdefined as a 3-bit field. However, the present invention is not limitedto this. For example, a field of four or more bits or two or less bitsmay be provided as the Version subfield. Also, the information of theVersion may be notified at a position other than the 0th to second bitsof the EHT-SIG-A1 field. In the examples of Tables 1 to 6, the Versionsubfield is provided in the EHT-SIG-A1. However, the subfield may beprovided in another place. For example, an additional signal field maybe provided before the EHT-SIG-A described above (for example,immediately after the L-LTF field or the L-SIG field), and the Versionsubfield may be newly included in the field. In an example, the newfield can be arranged before the RL-SIG field. This makes it possible todiscriminate the type of the standard of the frame at an earlier stageand obviate the necessity of analyzing subsequent frames. Due to thisreason, the calculation time and power consumption needed for analyzingthe frame can be suppressed.

Note that although a radio frame of IEEE802.11EHT has been describedabove, the same configuration can be employed even in a successorstandard after IEEE802.11EHT. That is, for example, the above-describedconfiguration in which a predetermined number of bits at a correspondingposition of a field corresponding to the EHT-SIG-A store informationindicating the type (version) of the standard can be employed even in aradio frame corresponding to a new communication standard. Similarly,the configuration in which a new field for setting informationindicating the type of the standard is provided after the L-SIG (orRL-SIG) may be employed in a radio frame corresponding to a newcommunication standard. When a radio frame is received, thecommunication device can decode the radio frame up to the informationindicating the type of the standard and then discard the radio framebased on the fact that the radio frame is generated in accordance with astandard the self-device does not comply with. Note that in addition tothe AP 102 and the STAs 103 to 105, which are communication devices, aninformation processing device (for example, a radio chip) for generatingthe above-described PHY preamble can implement the present invention.

According to the present invention, it is possible to prevent acommunication device from unnecessarily continuing to read a radio frameupon receiving a radio frame complying with a standard to which thedevice is not adaptable.

OTHER EMBODIMENTS

Embodiment(s) of the present invention can also be realized by acomputer of a system or apparatus that reads out and executes computerexecutable instructions (e.g., one or more programs) recorded on astorage medium (which may also be referred to more fully as a‘non-transitory computer-readable storage medium’) to perform thefunctions of one or more of the above-described embodiment(s) and/orthat includes one or more circuits (e.g., application specificintegrated circuit (ASIC)) for performing the functions of one or moreof the above-described embodiment(s), and by a method performed by thecomputer of the system or apparatus by, for example, reading out andexecuting the computer executable instructions from the storage mediumto perform the functions of one or more of the above-describedembodiment(s) and/or controlling the one or more circuits to perform thefunctions of one or more of the above-described embodiment(s). Thecomputer may comprise one or more processors (e.g., central processingunit (CPU), micro processing unit (MPU)) and may include a network ofseparate computers or separate processors to read out and execute thecomputer executable instructions. The computer executable instructionsmay be provided to the computer, for example, from a network or thestorage medium. The storage medium may include, for example, one or moreof a hard disk, a random-access memory (RAM), a read only memory (ROM),a storage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™),a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

1. A communication device that transmits or receives a radio frame including a preamble and a data field of a physical layer (PHY), wherein the preamble includes an L-STF (Legacy Short Training Field), an L-LTF (Legacy Long Training Field), an L-SIG (Legacy Signal Field), an EHT-SIG-A (Extremely High Throughput Signal A Field), an EHT-STF (EHT Short Training Field), and an EHT-LTF (EHT Long Training Field), and the EHT-SIG-A includes a field indicating a standard that the radio frame complies with. 2.-19. (canceled) 